The proposed program would complete the development and fabrication of a Seldinger catheter/insertion sheath from our softenable, Shape-Memory Thermoplastic (SMT). The SMT would be compounded and pelletized, then extruded as a high modulus, thin-walled, radiopaque tube, which is post- formed to have an approximately 16 gauge distal tip. The remainder of the catheter body would be 8F or larger. Upon reaching 37 degrees C, the tapered tip would expand to the larger diameter of the proximal end of the sheath, to permit catheter insertion with an optional guide wire. During expansion, the SMT undergoes a stiffness reduction, which should help reduce intimal damage and thrombosis. The biostability, toxicity and thromboresistance will be determined for the optimized compound. Functionality and performance testing of the assembled device will be determined by implanting prototype devices into sheep carotid arteries. A packaging system will be developed to insure that the cold-formed introducer does not expand during shipment and a material Master File will be submitted to the FDA. The shape-memory Seldinger catheter/sheath should be useful for rapid insertion of a variety of diagnostic and therapeutic devices, including radiography catheters, intraaortic balloons, femoral shunts, angioplasty devices and catheter-mounted blood pumps.